Comparison And Interpretation Of Logging Evaluation Methods For Shale Oil And Gas Desserts

With the continuous progress of science and technology,shale gas exploration of China has made great breakthroughs,showing great exploration and development potential.Shale gas reservoirs and conventional oil and gas reservoirs have great differences in electrical properties and reservoir physical properties.However,shale gas logging interpretation methods are lacking.The theoretical system of "sweet spot" of rock gas is of great significance for improving the economic benefits of shale gas exploration and guiding the exploration and development of shale gas.This study mainly carried out dessert prediction analysis on the Xujiahe Formation to Meitan Formation in Fuling area,eastern Sichuan,and analyzed the total organic carbon content,porosity and water saturation,respectively,as well as the organic shale free oil content,Oil and gas fractures and rock brittleness logging parameter method calculation,and the most feasible parameters and calculation methods are proposed by comparison.Comparing the results calculated based on the "four pores" model in the study area,it is found that the total porosity calculated by the Sondergeld model method and the Utley model is not much different,but the value calculated by the volume model method has a large deviation because it is more susceptible to changes in bore influences.In addition,by comparing the evaluation results with the actual data,it is found that the calculation method of fracture porosity based on double lateral resistivity is generally reliable,while the calculation results of organic porosity are more reliable.The results of studies on saturation show that the results of different calculation methods are quite different,and the calculation parameters have a greater impact on the results.Except for the results of the Simandoux formula,the results of water saturation calculated by other methods are similar,but the value is too large.The overall result of the Simandoux formula calculation is small,and in the well section with porosity close to the rock salt,the calculated water saturation is extremely small or even no value,which is more in line with the geological rules,indicating that the Simandoux formula calculation method is feasible and the calculation parameters are reasonable The calculation results are reliable.In terms of free oil content,it is found through calculation that free oil content is greatly affected by water saturation.Before calculating this parameter,a detailed analysis of water saturation(or oil saturation)is required.In terms of related logging parameters,the study found that the calculation results of mud content are reliable,and the calculation method of shear wave time difference is feasible and reliable;in the calculation of total organic carbon content,a single empirical formula based on natural potential,based on acoustic wave time difference and deep induction The intersection of the TOC results calculated by the traditional resistivity and the improved Δlog R method and the core experiment results.The calculation of the TOC and the core TOC of the three methods are in good agreement,but the TOC results calculated by the three methods are between When comparing,it is found that the TOC morphology calculated by the traditional Δlog R method and the improved Δlog R method are similar,and the error of the TOC measurement value of the core is smaller than that of the single empirical formula based on natural potential;through the traditional and Compared with the TOC results calculated by the improved Δlog R method,it is found that the error between the TOC calculated by the improved Δlog R method and the core TOC is smaller than the error of the traditional Δlog R method.It can be seen that the optimization of the scale factor greatly improves the accuracy of the Δlog R method to calculate the organic carbon content.Finally,the TOC results obtained by the two methods are intersected with the core experiment results,and it is found that the calculation of the improved Δlog R method has better consistency with the core TOC than the traditional Δlog R method.